Re: [PATCH][2.6.8-rc1-mm1] drivers/scsi/sg.c gcc341 inlining fix

Matthew Wilcox
2004-07-15T15:58:24Z

On Thu, Jul 15, 2004 at 09:09:38AM -0400, Jeff Garzik wrote:
> >Compilers for top-down (define-before-use) languages like C
> >have traditionally also worked in a top-down fashion, processing
> >one top-level declaration at a time. Forward references are
> >either errors, or are (when a proper declaration is in scope)
> >left to the linker to resolve.
> >
> >Processing an entire compilation-unit (e.g. whole C file)
> >as a single unit is typically _only_ done when either the
> >language semantics requires it (not C, but e.g. Haskell),
> >or when very high optimisation levels are requested.
>
> Or in the case where you parse the entire file, then generate code for
> the entire file in a separate pass. Which does NOT imply
> unit-at-a-time, for the readers at home. It just implies generation of
> the AST.

... which GCC didn't use to do. It used to generate RTL directly from
the source. From the GCC news and announcements page:

October 5, 2001
Alexandre Oliva of Red Hat has generalized the tree inlining
infrastructure, formerly in the C++ front end, so that it is now
used in the C front end too.

> >In the case of gcc-3.4.1 failing to inline, you are asking
> >gcc to do something (peeking forward) which it never has
> >promised to do. And with the kernel using -fno-unit-at-a-time
> >for stack conservation reasons, gcc is actually being _told_
> >not to do global compilation.
> >
> >This is not a gcc bug, nor is it being "exceedingly dumb".
>
> Actually, yes it is.

No, it's not. It's always been this way. You seemed to ignore that
message I posted yesterday.

--
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the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
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he enjoys after this process of grotesque self-deception." -- Mark Twain